People don't like to admit this, but "offensive" is by definition subjective (to whom does this give offense?).

Thus, unless you're fairly explicit about who it's not okay to offend, "offensive" is at best vague and at worst weasel-wording.

It is, however, common knowledge that calling that particular person orange is meant as an insult. No need to have a precise definition of "offensive" for cases like that.

I, as non USAer, have no idea what is the relation between Trump and orange.

I tried naming a particular shade of brown "solid poop" and it was rejected. I feel let down.

Trump can be a word meaning “done better”. I trumped you at math.

Trump does make an effort to be orange. It’s sort of a trade mark like John Deere green.